Anti-factor VIII antibodies in brothers with haemophilia A share similar characteristics.

INTRODUCTION: The development of neutralizing antibodies (inhibitors) against coagulation factor VIII (FVIII) is currently the most serious complication for patients with haemophilia A undergoing FVIII replacement therapy. Several genetic factors have been acknowledged as risk factors for inhibitor development. AIM: To analyze the influence of genetic factors on the nature of the humoral immune response to FVIII in eight brother pairs with inhibitors. METHODS: The domain specificity of FVIII-specific IgG was analysed by antibody binding to FVIII fragments and homologue-scanning mutagenesis (HSM). The FVIII-specific IgG subclasses were measured by direct ELISA. RESULTS: Of the 16 patient analysed with both methods, 12 had A2- and 13 had C2-specific IgG. The presence of A1-, A3- or C1-specific IgG was identified in nine of 14 patients analysed by HSM. IgG1, IgG2 and IgG4 subclasses contributed to the anti-FVIII IgG response, and the amount of FVIII-specific IgG1 (r = 0.66) and IgG4 (r = 0.69) correlated significantly with inhibitor titres. Patients with high concentrations of total anti-FVIII IgG (r = 0.69) or high inhibitor titres (r = 0.52) had a high proportion of FVIII-specific IgG4. Statistical analysis revealed trends/evidence that the subclass distribution (P = 0.0847) and domain specificity to HC/LC (P = 0.0883) and A2/C2 (P = 0.0011) of anti-FVIII IgG were more similar in brothers compared to unrelated subjects. CONCLUSION: Overall, our data provide a first hint that anti-FVIII IgG characteristics are comparable among haemophilic brothers with inhibitors. Whether genetic factors also influence the nature of patients' antibodies needs to be confirmed in a larger study population.

Prompt immune tolerance induction at inhibitor diagnosis regardless of titre may increase overall success in haemophilia A complicated by inhibitors: experience of two U.S. centres.

Current guidelines recommend delaying the start of immune tolerance induction (ITI) until the inhibitor titre is <10 Bethesda units (BU) to improve success. This study was conducted to evaluate ITI outcome relative to time to start ITI from inhibitor detection irrespective of inhibitor titre. Data were retrospectively collected from two U.S. haemophilia treatment centres (HTCs) on subjects with severe/moderate factor VIII (FVIII) deficiency with inhibitors who underwent ITI. Outcomes were defined pragmatically: success--negative inhibitor titre and ability to use FVIII concentrate for treatment/bleed prevention; partial success--inhibitor titre 1 to <5 BU with ability to use FVIII concentrate for treatment of bleeding; failure--ITI ongoing >3 years without achieving success/partial success, or ITI discontinuation. Fifty-eight subjects were included; 32 of 39 (82%) with high-responding inhibitor (HRI) achieved success, 7 failed. HRI subjects were subdivided based on ITI start time: 23/39 subjects started within 1 month of detection and 22/23 (96%) achieved success. Of these 23, 13 started ITI with an inhibitor titre ≥10 BU; all were successes. Eleven of 39 HRI subjects had an interval >6 months until ITI start; 7 (64%) achieved success. Time from inhibitor detection to ITI start may play a critical role in outcome. A titre ≥10 BU at ITI start did not influence outcome in subjects when ITI was initiated within 1 month of detection. Prompt ITI should be considered a viable therapeutic option in newly identified patients with inhibitors regardless of current inhibitor titre.

A haemophilia disease management programme targeting cost and utilization of specialty pharmaceuticals.

The high cost of clotting factor concentrate (CFC) used to treat haemophilia and von Willebrand disease (VWD) attracts health plans' attention for cost management strategies such as disease management programmes (DMPs). In 2004, Indiana's high risk insurance health plan, the Indiana Comprehensive Health Insurance Association, in partnership with the Indiana Hemophilia and Thrombosis Center developed and implemented a DMP for beneficiaries with bleeding disorders. This report evaluates the effectiveness of the DMP 5 years post implementation, with specific emphasis on the cost of CFC and other medical expenditures by severity of disease. A pre/post analysis was used. The main evaluation measures were total cost, total outpatient CFC IU dispensed and adjusted total outpatient CFC cost. Summary statistics and mean and median plots were calculated. Overall, 1000 non-parametric bootstrap replicates were created and percentile confidence limits for 95% confidence intervals (CI) are reported. Mean emergency department (ED) visits and mean and median duration of hospitalizations are also reported. The DMP was associated with a significant decrease in mean annualized total cost including decreased CFC utilization and cost in most years in the overall group, and specifically in patients with severe haemophilia. Patients with mild and moderate haemophilia contributed little to overall programme expenditures. This specialty health care provider-administered DMP exemplifies the success of targeted interventions developed and implemented through a health care facility expert in the disease state to curb the cost of specialty pharmaceuticals in conditions when their expenditures represent a significant portion of total annual costs of care.

Antibody formation and specificity in Bethesda-negative brother pairs with haemophilia A.

Antibodies directed towards non-neutralizing epitopes on the factor VIII protein (FVIII) may be detected in patients with haemophilia A. We evaluated the prevalence of non-neutralizing antibodies, in 201 inhibitor-negative brother pairs with severe haemophilia A, enrolled in the Malmö International Brother Study and the Haemophilia Inhibitor Genetics Study. To evaluate binding specificity of the antibodies, ELISA plates were coated with two recombinant full-length (FL) FVIII-products and one recombinant B-domain-deleted (BDD) product. Seventy-nine patients (39.3%) had a history of positive inhibitor titre measured by Bethesda assay, and FVIII antibodies were detected in 20 of them (25.3%). Additional 23 samples from subjects without a history of FVIII inhibitors were ELISA-positive corresponding to a frequency of non-neutralizing antibodies of 18.9%. The antibody response towards the different FVIII products was heterogenous, and was raised not only towards the non-functional B-domain but also towards both FL-rFVIII and BDD-rFVIII. In patients considered successfully treated with immune tolerance induction, 25.4% had remaining FVIII antibodies. The number of families with an antibody response in all siblings was increased when the total antibody response was taken into account, further supporting the concept of a genetic predisposition of the immune response. Further studies and careful monitoring over time are required to appreciate the immune response on the risk of inhibitor development or recurrence in the future.

F8 haplotype and inhibitor risk: results from the Hemophilia Inhibitor Genetics Study (HIGS) Combined Cohort.

Ancestral background, specifically African descent, confers higher risk for development of inhibitory antibodies to factor VIII (FVIII) in haemophilia A. It has been suggested that differences in the distribution of FVIII gene (F8) haplotypes, and mismatch between endogenous F8 haplotypes and those comprising products used for treatment could contribute to risk. Data from the Hemophilia Inhibitor Genetics Study (HIGS) Combined Cohort were used to determine the association between F8 haplotype 3 (H3) vs. haplotypes 1 and 2 (H1 + H2) and inhibitor risk among individuals of genetically determined African descent. Other variables known to affect inhibitor risk including type of F8 mutation and human leucocyte antigen (HLA) were included in the analysis. A second research question regarding risk related to mismatch in endogenous F8 haplotype and recombinant FVIII products used for treatment was addressed. Haplotype 3 was associated with higher inhibitor risk among those genetically identified (N = 49) as of African ancestry, but the association did not remain significant after adjustment for F8 mutation type and the HLA variables. Among subjects of all racial ancestries enrolled in HIGS who reported early use of recombinant products (N = 223), mismatch in endogenous haplotype and the FVIII proteins constituting the products used did not confer greater risk for inhibitor development. Haplotype 3 was not an independent predictor of inhibitor risk. Furthermore, our findings did not support a higher risk of inhibitors in the presence of a haplotype mismatch between the FVIII molecule infused and that of the individual.

Extended IL10 haplotypes and their association with HIV progression to AIDS.

Interleukin-10 (IL-10) is a pleiotropic cytokine with both immunosuppressive and immunostimulatory functions. Its roles in infections and autoimmunity may have resulted in selective pressures on polymorphisms within the gene, leading to genomic coexistence of several semi-conserved haplotypes involved with diverse pathogen interactions during genomic evolution. Previous studies focused either exclusively on promoter haplotypes or on individual SNPs. We genotyped 21 single nucleotide polymorphisms in the human IL10 gene and examined this variation compared to other mammalian species sequences. Haplotype heterogeneity in human populations is centered around 'classic' 'proximal' promoter polymorphisms: -592, -819 and -1082. High-producing GCC haplotypes are by far the most numerous and diverse group, the intermediate IL-10 producing ACC-inclusive haplotypes seem to be related most closely to the ancestral haplotype, and the ATA-inclusive haplotypes cluster a separate branch with strong bootstrap support. We looked at associations of corresponding haplotypes with HIV progression. A haplotype trend regression confirmed that individuals carrying the low-producing ATA-inclusive haplotypes in European Americans progress to AIDS faster, and most likely explain the role of IL10. Our findings are consistent with the hypothesis that existing polymorphisms in this gene may reflect a balance of historic adaptive responses to autoimmune, infectious and other disease agents.

Genetic restriction of HIV-1 infection and progression to AIDS by a deletion allele of the CKR5 structural gene. Hemophilia Growth and Development Study, Multicenter AIDS Cohort Study, Multicenter Hemophilia Cohort Study, San Francisco City Cohort, ALIVE Study.

The chemokine receptor 5 (CKR5) protein serves as a secondary receptor on CD4(+) T lymphocytes for certain strains of human immunodeficiency virus-type 1 (HIV-1). The CKR5 structural gene was mapped to human chromosome 3p21, and a 32-base pair deletion allele (CKR5Delta32) was identified that is present at a frequency of approximately0.10 in the Caucasian population of the United States. An examination of 1955 patients included among six well-characterized acquired immunodeficiency syndrome (AIDS) cohort studies revealed that 17 deletion homozygotes occurred exclusively among 612 exposed HIV-1 antibody-negative individuals (2.8 percent) and not at all in 1343 HIV-1-infected individuals. The frequency of CKR5 deletion heterozygotes was significantly elevated in groups of individuals that had survived HIV-1 infection for more than 10 years, and, in some risk groups, twice as frequent as their occurrence in rapid progressors to AIDS. Survival analysis clearly shows that disease progression is slower in CKR5 deletion heterozygotes than in individuals homozygous for the normal CKR5 gene. The CKR5Delta32 deletion may act as a recessive restriction gene against HIV-1 infection and may exert a dominant phenotype of delaying progression to AIDS among infected individuals.

Genetic restriction of AIDS pathogenesis by an SDF-1 chemokine gene variant. ALIVE Study, Hemophilia Growth and Development Study (HGDS), Multicenter AIDS Cohort Study (MACS), Multicenter Hemophilia Cohort Study (MHCS), San Francisco City Cohort (SFCC)

Stromal-derived factor (SDF-1) is the principal ligand for CXCR4, a coreceptor with CD4 for T lymphocyte cell line-tropic human immunodeficiency virus-type 1 (HIV-1). A common polymorphism, SDF1-3'A, was identified in an evolutionarily conserved segment of the 3' untranslated region of the SDF-1 structural gene transcript. In the homozygous state, SDF1-3'A/3'A delays the onset of acquired immunodeficiency syndrome (AIDS), according to a genetic association analysis of 2857 patients enrolled in five AIDS cohort studies. The recessive protective effect of SDF1-3'A was increasingly pronounced in individuals infected with HIV-1 for longer periods, was twice as strong as the dominant genetic restriction of AIDS conferred by CCR5 and CCR2 chemokine receptor variants in these populations, and was complementary with these mutations in delaying the onset of AIDS.

Value added: increasing the power to assess treatment outcome in joint haemorrhages.

Subject reports of efficacy of treatment of haemophilia-related joint bleeding are by definition subjective, yet are often the primary outcome in studies comparing therapies. Verbal descriptors such as effective, partially effective, poorly effective, not effective are treated as dichotomous or categorical variables in analyses, lowering the statistical power relative to that which might be achieved with a continuous variable. The aims of this study were to examine reports of pain recorded on a 100-mm visual analogue scale (VAS) during the course of joint bleeding; determine whether pain varied by treatment period among pairs reporting discordant outcomes on a verbal scale (one product effective, the other not effective); test whether the two products under study were equivalent with respect to VAS scores; and evaluate their relationship to verbal reports of efficacy. Data from the international, prospective, randomized, crossover FEIBA NovoSeven Comparative study of two bypassing agents used for treatment of 96 bleeding episodes in 48 participants were examined. VAS scores were associated with verbal descriptors of efficacy at every time point, and were equivalent between treatment periods. There were differences in mean scores at time points at which participants rated one treatment effective, the other not effective. As a continuous variable, the VAS score may have more power than a dichotomous variable and when used with verbal descriptions of efficacy can improve the overall accuracy of assessment. This report highlights an important consideration in the selection of outcome measurement that can be generalized to other haemophilia treatment research.

Diminished frequency of hepatitis C virus specific interferon gamma secreting CD4+ T cells in human immunodeficiency virus/hepatitis C virus coinfected patients.

BACKGROUND: Human immunodeficiency virus/hepatitis C virus (HIV/HCV) coinfection is a common and complex clinical problem in which loss of immunological control of HCV occurs, with increased HCV viral load and more aggressive liver disease. Cellular immune responses, particularly secretion of interferon gamma (IFN-gamma) appear to be important in the control of HCV, and a detectable HCV specific CD4 response is associated with clearance of the virus. HCV specific CD8+ T cell responses, weak in chronic HCV infection, have been shown to be further impaired in HIV coinfection and this CD8+ T cell deficiency is related to the decline in CD4 T cell count. AIMS: To compare the CD4 T cell response to HCV in HIV/HCV coinfected and HCV monoinfected individuals and to determine the relationship of responses with declining CD4 count. PATIENTS: The study subjects were a cohort of 68 HCV monoinfected and 67 HCV/HIV coinfected haemophiliac children and adolescents (the Hemophilia Growth and Development Study) who were followed for a seven year period. METHODS: We analysed IFN-gamma secreting CD4+ responses to HCV proteins and peptides and HIV p24 antigen using an ELISpot assay. RESULTS: We found a significant decrease in HCV specific responses among those who were HIV coinfected (10/67 v 36/68; p<0.0001) both in numbers of responders and frequency of specific cells. This did not appear to be closely related to CD4 count. CONCLUSIONS: The reduction in HCV specific CD4 T cells in coinfection provide a cellular mechanism for the loss of control of HCV in coinfected individuals, even in those with relatively preserved CD4+ T cell counts and CD4+ T cell responses to HIV.

Prophylaxis escalation in severe von Willebrand disease: a prospective study from the von Willebrand Disease Prophylaxis Network.

BACKGROUND: Treatment of mucosal bleeding (epistaxis, gastrointestinal bleeding, and menorrhagia) and joint bleeding remains problematic in clinically severe von Willebrand disease (VWD). Patients are often unresponsive to treatment (e.g. desmopressin or antifibrinolytic therapy) and may require von Willebrand factor (VWF) replacement therapy. There are little data on the use of prophylaxis in VWD, and none have been applied in a prospective, treatment escalation design. OBJECTIVE: Evaluate the effect of escalating dose prophylaxis in severe VWD. METHODS: Patients eligible for enrollment in this prospective study included those with type 1 VWD with VW factor activity-ristocetin cofactor ratio ≤ 20% and unresponsive to desmopressin, patients with type 2 VWD not responsive to desmopressin and all subjects with type 2B and type 3 VWD. Entry criteria were strictly defined, as were therapy escalation parameters and clinical data collection. RESULTS: Eleven subjects completed the study. Six had type 2A, and five had type 3 VWD. Six patients presented with epistaxis, three with GI bleeding, and two with joint bleeding. Seven had dose escalation above the first level. Among the 10 subjects with evaluable bleeding log data, use of prophylaxis decreased the median annualized bleeding rate from 25 to 6.1 (95% confidence interval of the rate difference: -51.6 to -1.7), and the median annualized bleeding rate was even lower (4.0; 95% confidence interval: -57.5 to -5.3) when the subjects reached their final dosing level. CONCLUSION: This is the first prospective study to demonstrate that prophylaxis with VW factor concentrates is highly effective in reducing mucosal and joint bleeding rates in clinically severe VWD.

Physical activity by socioeconomic status in two population based cohorts.

In the current study, we examined physical activity in two population based cohorts of Allegheny County. Pennsylvania, which differed markedly in their socioeconomic status (SES), in order to evaluate the relationship of SES to physical activity patterns. A total of 917 individuals participated in a prevalence survey administered during a home visit in 1981. All of the participants were white. Households were randomly selected. An overall response rate of 84% was achieved. Activity was assessed using the Paffenbarger survey, which included the number of blocks walked, stairs climbed, sports and recreational activities, and hours spent in vigorous, moderate, and light activities. In both high and low SES individuals, activity was inversely associated with age and was higher in males than in females. The relationship of physical activity to SES differed depending on the dimension of activity assessed. Participation in sports was reported more frequently in high status males and females. SES was a significant predictor of walking activity in females, with low status females reporting more walking. The number of hours spent in moderate activities was greater, but the number of hours spent in light activities was lower, in low status males. There was little difference by SES in the composite activity score, average annual kilocalories per week. In summary, our research suggests that SES can impinge differently on separate manifestations of activity, and future research needs to identify how SES affects activity.

Detecting AIDS restriction genes: from candidate genes to genome-wide association discovery.

The screening of common genetic polymorphisms among candidate genes for AIDS pathology in HIV exposed cohort populations has led to the description of 20 AIDS restriction genes (ARGs), variants that affect susceptibility to HIV infection or to AIDS progression. The combination of high-throughput genotyping platforms and the recent HapMap annotation of some 3 million human SNP variants has been developed for and applied to gene discovery in complex and multi-factorial diseases. Here, we explore novel computational approaches to ARG discovery which consider interacting analytical models, various genetic influences, and SNP-haplotype/LD structure in AIDS cohort populations to determine if these ARGs could have been discovered using an unbiased genome-wide association approach. The procedures were evaluated by tracking the performance of haplotypes and SNPs within ARG regions to detect genetic association in the same AIDS cohort populations in which the ARGs were originally discovered. The methodology captures the signals of multiple non-independent AIDS-genetic association tests of different disease stages and uses association signal strength (odds ratio or relative hazard), statistical significance (p-values), gene influence, internal replication, and haplotype structure together as a multi-facetted approach to identifying important genetic associations within a deluge of genotyping/test data. The complementary approaches perform rather well and predict the detection of a variety of undiscovered ARGs that affect different stages of HIV/AIDS pathogenesis using genome-wide association analyses.

Long-term major joint outcomes in young adults with haemophilia: interim data from the HGDS.

A study of major joint outcomes, specifically range of motion and synovitis, was conducted with data from a subset of adolescents enrolled in the prospective Hemophilia Growth and Development Study (HGDS). Clinical observations were carried out over a 7-year period from 1989 to 1996. A secondary aim was to gain insight into factors that might influence decisions regarding maintaining or discontinuing prophylaxis during early adulthood. Twenty-nine participants (median age 17.4 at entry) were included. Median follow-up was 7 years (range: 4.8-7.7). Range of motion (ROM) and synovitis in six major joints (knees, elbows and ankles), were evaluated by physical examination every 6-12 months. At the baseline observation, 73.6% of joints showed no ROM abnormalities or synovitis, and all joints were normal in 11 patients. Of the 11 participants, 54.5% developed abnormalities and 28.1% of normal joints at baseline became abnormal during the follow-up. Ankles were the most severely affected and had persistent progression during late adolescence and adulthood. Elbows and knees did not show progression after the first few years of the follow-up. The progression of haemophilic arthropathy in adolescents and young adults varies from individual to individual and also in the site of affected joints. In view of this, the decision regarding discontinuation of prophylaxis in patients with haemophilia should be individualized.

Effect of myeloablative bone marrow transplantation on growth in children with sickle cell anaemia: results of the multicenter study of haematopoietic cell transplantation for sickle cell anaemia.

Although haematopoietic cell transplantation (HCT) is curative for sickle cell anaemia (SCA), concerns about its short- and long-term toxicities limit its application. A potential toxicity is an adverse effect on growth. To identify an HCT growth effect, serial height and weight measurements from 53 children and adolescents with SCA after receiving a transplant were compared to historical controls. Hierarchical Linear Models for longitudinal data were used for analysis. In general growth was not impaired by HCT for SCA in young children; however, diminished growth may occur if HCT is carried out near or during the adolescent growth spurt.

Hepatitis C virus infection and neurocognitive function.

Hepatitis C virus (HCV) infection may be associated with neurocognitive deficits. The Hemophilia Growth and Development Study enrolled HIV-infected and HIV-uninfected patients and a group of nonhemophiliac siblings. After controlling for multiple factors, HCV monoinfection was not associated with deficits in adaptive behavior, intelligence, or attention/concentration.